This thread sorta fits a theory I came up with over at The Avengers sequel's news & spec thread. Perhaps, the mind gem is in fact used in the scepter Thanos gave Loki. And considering the scepter was last seen in Black Widow's hand, SHIELD may still l have it.

And in Guardians of the Galaxy, if Thanos is ultimately gathering the infinity gems then, getting the mind gem back could give him a reason to come to earth in The Avengers sequel. Just a theory.

Well, a lot of us, myself included, speculated that the Mind Gem was in Loki's sceptre, and everything in the Avengers movie certainly bolsters that theory, even if it doesn't directly say so.

But here's the thing: Thanos *gave* the sceptre to Loki. (The Other says so.) So why would he *give away* an Infinity Gem? Especially if he was secretly betting on Loki to lose his war on Earth anyway?